1. Field of the Invention
The present invention generally relates to a noise reduction method and apparatus and, more particularly, to a noise reduction method and apparatus using a luminance value of a target pixel and luminance values of neighboring pixels of the target pixel so as to identify and eliminate a noise point of a digital image.
2. Description of the Prior Art
In digital image processing, the most generally used method to reduce noise is to directly process the pixels related to the image. For example, averaging filters and sequence statistical filters are used according to respective requirements.
Conventionally, impulse noise is eliminated using a median filter, which is a non-linear spatial filter operating corresponding to the pixel values in a neighboring region of a target pixel so as to sort the pixel values and then make the median pixel replace the target pixel. However, the median filter performs pixel adjustment for the entire image including some non-noise portions. Therefore, the noise reduction process using the median filter may lead to undesirable distortion of the image because it cannot identify where noise occurs. Moreover, since the pixel is adjusted according to the pixel values of the neighboring pixels, the adjusted image shows unnaturalness in luminance and chrominance.
Accordingly, the present invention provides a noise reduction method not only to identify noise of a digital image, but also to reduce noise by adjusting the luminance value and the chrominance value to avoid image distortion.
Compared to the prior art, the noise reduction method of the present invention exhibits excellent performance in noise reduction while remaining the original colors in the region where there is no noise determined.